Inositol or its phosphates and associated lipids are found in many foods, in particular fruit, especially cantaloupe and oranges.[4] In plants, the hexaphosphate of inositol, phytic acid or its salts, the phytates, serve as phosphate stores in seed, for example in nuts and beans.[5] Phytic acid also occurs in cereals with high bran content. Phytate is, however, not directly bioavailable to humans in the diet, since it is not digestible. Some food preparation techniques partly break down phytates to change this. However, inositol in the form of glycerophospholipids, as found in certain plant-derived substances such as lecithins is well-absorbed and relatively bioavailable.

Myo-inositol (free of phosphate) was once considered a member of the vitamin B complex, called Vitamin B8 in this context. However, because it is produced by the human body from glucose, it is not an essential nutrient.[6]

In its most stable conformation, the myo-inositol isomer assumes the chair conformation, which moves the maximum number of hydroxyls to the equatorial position, where they are farthest apart from each other. In this conformation, the natural myo isomer has a structure in which five of the six hydroxyls (the first, third, fourth, fifth, and sixth) are equatorial, whereas the second hydroxyl group is axial.[8]

Function

Inositol, phosphatidylinositol and some of their mono- and polyphosphates function as secondary messengers in a number of intracellular signal transduction pathways. They are involved in a number of biological processes, including:

Inositol penta- (IP5), tetra- (IP4), and triphosphate (IP3) are also called "phytates".

Use in explosives manufacture

At the 1936 meeting of the American Chemical Society, professor Edward Bartow of the University of Iowa presented a commercially viable means of extracting large amounts of inositol from the phytic acid naturally present in waste corn. As a possible use for the chemical, he suggested 'inositol nitrate' as a more stable alternative to nitroglycerin.[21] Today, inositol nitrate is used to gelatinize nitrocellulose, thus can be found in many modern explosives and solid rocket propellants.[22]

Counter to road salt

When plants are exposed to increasing concentrations of road salt, the plant cells become dysfunctional and undergo apoptosis, leading to inhibited growth. Inositol pretreatment could reverse these effects.[23][24]

Research and clinical applications

Large doses of inositol have been studied for treatment of depression, but insufficient evidence exists to determine whether this is an effective treatment.[25]

Inositol is also used as a stand-in for cocaine in television shows and in film.[30]

Nutritional sources

Myo-Inositol is naturally present in a variety of foods, although tables of food composition do not always distinguish between lecithin, the bioavailable form, and the unavailable phytate form in grains.[4] Foods containing the highest concentrations of myo-inositol (including its compounds) include fruits, beans, grains, and nuts.[4] Beans and grains, however, contain large amounts of phytate.

^Reynolds, James E. F. (January 1, 1993). Martindale: The Extra Pharmacopoeia. 30. Pennsylvania: Rittenhouse Book Distributors. p. 1379. ISBN0-85369-300-5. An isomer of glucose that has traditionally been considered to be a B vitamin although it has an uncertain status as a vitamin and a deficiency syndrome has not been identified in man